This sounds like an old story: grandpa's gun from the war, stashed in the attic where nobody (including the government) knew about it, discovered after he died and the heir doesn't even have a licence. Correct me if those details are wrong, but if your boss had an RPAL he wouldn't be using that ‘records lost in the war’ line.
It's a nifty looking and desireable piece, but unfortunately in Canada it is caught up in a bunch of complications.
The PPK in its original configuration will be Prohibited by barrel length (hand-gun under 105mm), known as 12(6.1) classification [or just 12(6)]. If the owner doesn't have 12(6) on his RPAL card, he cannot legally own it, and there is no way to get 12(6) status at this point in time. Such hand-guns produced prior to 1946 (World War II and earlier) can be inherited by direct family only (child, grand-child, spouse, or sibling), under
Section 12(7) of the Firearms Act, so either your boss has a 12(6) PAL, or he
might be eligible for one (under possession only).
Since the gun was property in the estate of the grand-father, if it was a legally owned gun it can be held by the executor of the estate for a reasonable time to arrange its disbursal, which will entail getting its papers in order (and a possible 12(7) heir licensed). If the gun was not registered under the current system, or the one which preceded it (green registration slips), the CFC won't consider it eligible to add as a new registration into their system of Prohibited fire-arms; if it comes to the attention of the Law, it will be confiscated.
Your boss should know that it is a highly controlled item, and the fact it was grandpa's old relic doesn't protect people from the many offences in the Criminal Code that deal with Prohibited Firearms, un-licensed possession, and more. As a Registered hand-gun, it can only be possessed, stored, transported, and so on in accordance with the restrictions of the Law, by a person with the proper licence and authorization. As an un-registered Prohib., you cannot own, transfer, or transport it
at all, even to a gun-smith for alterations to make it non-Prohib.
Don't know enough about non-civilian PPKs to give a price (besides, clear pictures including all numbers and markings would be required). A general guess on a 12(6) might be around half a thousand bucks, but this should be 12(7) eligible for inheritance, which makes for a slightly better market.